Planar magnetic transducers use a flat, lightweight diaphragm suspended in a magnetic field. The diaphragm in a planar magnetic transducer includes a conductive circuit pattern that, when energized, creates forces that move the diaphragm in the magnetic field to produce sound.
The conductive circuit pattern on the diaphragm can be created using multiple methods. In one approach, conducting wire is applied to the diaphragm base material, or substrate material.
In another approach, diaphragm material is created by laminating a very thin film with conductive material or foil or depositing a layer of conductive material on the film. The next step is to coat this film and foil laminate structure with a chemical resist mask. The film and foil laminate structure is placed in a bath containing the corrosive chemical compounds, allowing the chemical to eats away at the conductive material not concealed by the mask. The conductive material left behind comprises the desired traces.
It is desirable for an improved method for manufacturing thin film circuits for acoustic transducers that provides advantages absent in previous approaches